从文件异步加载图像

问题描述

我在本地存储的图像比较，我想展示给用户，而不会干扰用户界面线程。
我目前使用

I have an relatively image in local storage, I want to show it to the user without disturbing UI thread.I'm currently using

[[UIImage alloc] initWithContentsOfFile:path];

加载图像。

任何建议/帮助，请....

Any suggestions/help please....

推荐答案

如果你正在试图做的一切就是保持UI线程可用，成立了一个简短的方法来加载它在后台更新ImageView的完成时：

If all you're trying to do is keep the UI thread available, set up a short method to load it in the background and update the imageView when done:

-(void)backgroundLoadImageFromPath:(NSString*)path {
    UIImage *newImage = [UIImage imageWithContentsOfFile:path];
    [myImageView performSelectorOnMainThread:@selector(setImage:) withObject:newImage waitUntilDone:YES];
}

这presumes myImageView 是类的成员变量。现在，只需在任何线程在后台运行它：

This presumes myImageView is a member variable of the class. Now, simply run it in the background from any thread:

[self performSelectorInBackground:@selector(backgroundLoadImageFromPath:) withObject:path];

请注意，在 backgroundLoadImageFromPath 则需要等到 setImage：选择完成，否则后台线程的自动释放池在 setImage之前，可能释放图像：方法可以保留它

Note, in backgroundLoadImageFromPath you need to wait until the setImage: selector finishes, otherwise the background thread's autorelease pool may deallocate the image before the setImage: method can retain it.

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